DE3213756A1 - FLAP VALVE FOR PRESSURE TANK - Google Patents

Description

21.37ο

Flap valve for pressure vessels

MEROIER ACCUMULATOR CORPORATION, Dover, Delaware 199öl, USA

The invention relates to a flap valve for a pressure vessel, said pressure vessel being an envelope having a gas opening and a liquid opening which are opposite, a movable one within the Enclosure movable between the two openings and this having dividers separating different volumes into a gas region and a liquid region, said Flap valve has a shaft mounted movably in a guide and a shaft suitable for closing the liquid opening Has head.

In such pressure vessels, the gas area is initially filled with pressurized gas, which the movable separator against the Flap valve, which closes on the liquid opening of the pressure vessel, pushes back, filled. The gas area has then its greatest volume.

Then the liquid opening of the pressure vessel is with connected to a hydraulic system. Liquid under higher pressure than the pre-pressure is let into the liquid part, lifts the flap valve and pushes the movable separator back.

The container is then ready for use.

During normal operation, liquid can flow between the hydraulic system and the liquid part of the container once in the execution, which increases the volume of the liquid part of the container, and on the other hand in the return direction, whatever liquid returns to the hydraulic system flow.

During operation, the flap valve can be inadvertently closed in the direction of the suction effect of the Liquid outflow at fast return, for example at a flow rate of more than ten liters per second, acted upon will. Such closure can potentially be very sudden, and if it occurs multiple times, it can

this will affect the tightness of the container and its components. Since this closure can also occur during operation, there is a risk that it will damage the hydraulic system out of service.

The invention has for its object to provide a flap valve for a pressure vessel of the specified type in which the flap valve cannot close if during operation there is a return of liquid, even with very large flow rates, takes place, and this is solved by a very simple construction, at the same time in an automatic manner it is possible to carry out a complete emptying of the container slowly, for example for the requirements of maintenance or the test without the risk of damaging the isolator.

According to the invention, a flap valve for a pressure vessel of the specified type one through the stem of the flap valve and the guide in which said stem is movably mounted, limited fluid chamber of variable volume, said chamber decreasing in volume as the shaft penetrates, and wherein said chamber is provided by means of passage means having an opening in the vicinity of the flap valve head Connection pushes, wherein said flap valve is particularly characterized in that said passage devices on the one hand have means for interrupting the outflow of the liquid from said chamber in the event that this chamber decreases in volume and, on the other hand, means for slow drainage between said chamber and an active one Part of said means for interrupting the flow of liquid.

In particular, the said passage means are according to the invention equipped with a cylindrical portion provided with a seat at its opening of said passage means at the nearest end is liquid-tight, while the mentioned interruption devices one in this Ab--

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cut movably mounted and for loading by the ge named liquid for the purpose of bringing it up to the named tight seat for sealing after a reduction in volume of the named Chamber have suitable closure, said means for slow drainage, always connect the two parts of the section with a reduced cross-section, the two on both sides the locking device are attached.

In the case of a slow return of liquid from the tank in the direction of the hydraulic system, especially in the In conjunction with maintenance or inspection requirements, the slow flow means allow evacuation the variable volume chamber outwards without displacement of the closure member in the direction of its tight fit. That

The flap valve can thus close completely under the pushing action of the movable separator, resulting in complete emptying of the pressure vessel for maintenance or inspection without Ge. risk of damage to the movable isolator.

If, in the course of normal operation, there is a rapid return of liquid with a large flow rate between the pressure vessel and the hydraulic system comes about, causes the on the drain based suction effect in the flap valve a closing movement that tends to vary the volume of the chamber To reduce volume, which in turn presses the closure part on its tight fit, despite the means for slow Flow, the cross-section of which is too small to allow a considerable amount of liquid, via this route to escape. The liquid is accordingly prevented from leaving the variable volume chamber and after to be derived from outside. This forms an automatic hydraulic lock that prevents the flap valve from moving in During operation to place on the liquid opening of the pressure vessel and to close it. That way, each will The risk of unintentional closure and damage to such a flap valve are avoided.

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The particularly simple construction of the arrangement according to the invention, whose function runs automatically in particular without any complex arrangement / arrangement located outside the flap valve be noticed.

Furthermore, it will be noted that the invention is then of particular It is of interest when the volume of liquid from the pressure vessel that is taken up by the hydraulic installation den can, with a constant, below the maximum volume of the. Liquid part of the pressure vessel lying constant value i is predetermined in such a way that in the course of operation of the movable The separator always remains on this side of the flap valve.

According to a further feature of the invention, the cylindrical Liquid passage area at its opposite to the tight fit and closest to the variable volume chamber End of a support that serves as a support for the closure organ and tends to the latter by a light spring is withdrawn, said support being able to vary the flow of liquid between the chamber To allow volume and the cylindrical section even when the closure member is on the above-mentioned support.

Such a support can either consist of one for the closure member not tight seat or consist of a seat that can be tight in itself, but with an always open drainage channel connected between the chamber of variable volume and the cylindrical section, or made of a whole exist, which is formed by a non-tight seat and by a drainage channel.

The rest position of the closure member is formed, for example, by an end that forms a non-tight seat, a split one hollow pin or through a grooved end of a hollow pin, which also forms a non-tight fit. The end of the hollow pin can also form a seat that is inherently tight, and in this case a drainage channel is provided, for example in the pen in the form of a lateral

Bore and / or a bore can be provided in the stem of the flap valve.

Control devices for adjusting the height are preferred the rest position support provided, which are effective after the reaction time of the closing element and which, for example, a Have stacks of disks with more or less numerous disks or else a screw connection.

The closure member preferably consists of a ball, but it does can also consist of a plunger or be designed in any other suitable manner.

The flap valve of the pressure vessel has an opening the fluid opening of the pressure vessel «is acted upon by a spring. The force of this return spring can be chosen weak and only slightly higher than that which is necessary to taking into account the mass of the moving equipment and the friction and drag forces in the hydraulic area to compensate for the fact that the flap valve is blocked in the open position in the course of operation, like this was set out above.

It will be noted that in the absence of hydraulic blocking Device according to the invention, the return spring of the flap valve must be chosen very strongly to prevent premature closing avoiding the flap valve during operation, which reduces the risk of damage to the movable separator during emptying processes, especially for maintenance or inspection.

In a preferred embodiment, the fluid passage opening connected to the variable volume chamber is arranged directly below the flap valve head. Preferably, an annular baffle is placed under the flap valve head arranged to squeeze the turns of the return spring of the flap valve due to an outflow of a large Avoid amount of liquid at high speed. the

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fluid passage opening connected to the variable volume chamber is advantageously arranged inside this annular baffle, where the pressure is relatively low

Means for the slow passage can be carried out in any suitable way, for example thanks to a slight diametrical one Game between the closure member and the cylindrical passage section or in the form of either in the closure member or in the valve stem provided narrow channel.

Further features and advantages essential to the invention are derived from dea The following description, in which exemplary embodiments are explained with reference to the drawings. In the drawings demonstrate:

1 shows an overall view in longitudinal section of a pressure vessel provided with a flap valve according to the invention, wherein the middle part has been left out,

Fig. 2 is a view on a larger scale of the flap valve its liquid passage and the closing element in the open position, which slow emptying of the container enables

3 shows a view analogous to FIG. 2, but in which the closure member lies on its tight seat in the closed position and the closing of the flap valve by hydraulic Blockage prevents

4, § ", 6, 7, 8, 9 and 10 are views similar to FIG. 2, but each relating to seven variants.

First, reference is made to FIGS. 1 to 3, which, as a non-limiting exemplary embodiment of an application of the Invention to a pressure vessel formed by a pneumatic pressure accumulator.

The aforementioned pressure vessel has a dimensionally stable envelope 10 with a gas opening 11 and an opposite · Liquid opening 12 is provided.

The gas opening 11 receives a gas pressure loading valve 13 on which a movable divider 14, such as a deformable bladder, is connected. This extends inside the shell 10 between the openings 11 and 12 and divides this casing 10 into a gas area 15 and a liquid area 16, the volumes of which are variable.

The liquid opening 12 is given a cylindrical connection 17, which at its upper end has a conical, a seat 18 forming Edition forms. The connector 17 is internally provided with a central guide core 19 and has a circular shape Series of holes 21 on.

The central guide core or the guide 19 has a bore 22, 23, 24 / which is coaxial with the casing 10 (FIGS. 2 and 3) and successively from top to bottom a part of a large diameter 22, a part of a smaller diameter 23 and a part the diameter of which is slightly larger than that of the part 23.

A flap valve 25 has a head 26 which is suitable to close the liquid opening 12 by being on the conical seat 18 and on a movably mounted in the guide 19 Shank 27 comes to rest. In particular, the shaft 27 has a part of larger diameter 28 which is suitable to move in the part 22 of the guide 19, a part smaller Diameter 29 capable of moving in the part 23 of the guide 19 and having a threaded end 30. Lc-tztoros a ring 31 which is adapted to move in the bore part 24, while a nut 32 on the threaded end 30 is screwed to block the ring 31 on the shaft 27. It will be noted that when the flap valve 25 of 3 merges into the position of FIG. 2, the ring 31 penetrate into the bore part 24 with a dash-pot effect

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can, which makes it possible to slow down the ascent of the shaft 27.

The shaft 27 defines a chamber 33 with a variable in the guide 19 Volume. In particular, this chamber 33 is in the bore part 22 of the guide 19 around the part 29 of the shaft 27 and around formed below the part 28 of said shaft 27.

A liquid passage, indicated generally by 34, is provided in the flapper valve 25 and extends therebetween the chamber 33 and an opening 35 located in the vicinity of the head 26 of the flap valve 25. In particular, the said opening is located opening 35 directly below the head 26 where the pressure is relatively low.

In the embodiment shown in Figures 1 to 3, the liquid passage 34 has a diametrical channel 36, which is in communication with the chamber 33, and an axial channel provided in the shaft.

In the slightly widened part 38 of the channel 37, a hollow pin 39 split at 40 is mounted. The upper end 49 of the hollow Pin 39 defines a resting support which forms a non-tight seat for a sealing member 42. Said sealing member 42 forms a means for interrupting the flow of liquid and is described in detail below.

The liquid passage 34 also has a cylindrical one Section 43 with a larger diameter. Said cylindrical portion 4 3 is at the end with a dense Seat 44 is provided which is closest to the opening 35. Internally of the seat 44, a channel 45 which is in communication with the opening 35 is formed. The sealing member 42 is in Figures 1 to 3 a ball. Said ball 42 is movably mounted in the cylindrical section 43 and is suitable to be pushed by the liquid coming from the chamber 33 and to lie on the tight seat 44 to close. A light conical coil spring 46 tends to do the

To keep ball 42 pressed onto the non-tight seat 41, de is formed at the top of the split pin 39.

It will be noted that the ball 42 forms a type of reverse check valve which is located inside the large flap valve 25 is arranged.

Means for the slow passage of fluids with reduced Diameter form a permanent connection between the two parts 43A and 43B of section 43, which are on both sides of the ball 42 are arranged. In the example shown in Figures 1 to 3, these slow drain means consist of one slight diametrical play provided between the ball 42 and the cylindrical portion 43.

The maximum volume (Fig. 2) of the chamber variable "volume 33 is intended to be greater than the volume that is provided by the ball 42 between their non-tight seat 41 and their tight seat 44 shifted and takes into account the slight leaks caused by the play 47.

The time of movement of the ball 42 between the seats 41 and 44 is therefore provided very briefly in order to virtually immediately hydraulic blocking of the flap valve 25 in the event of a to ensure rapid return of liquid between the area 16 and the hydraulic system connected to the connection 17. This time can be very short thanks to the fact that the counter pressure after the opening 35 due to the arrangement of this The opening 35 under the head 26 of the flap valve 2 5 is relatively small and that the movement of the flap valve is only slight through the leaks resulting from the game 47 is slowed down.

A guide plate 48 is arranged around the shaft 27 below the head 26 of the flap valve 25. The said guide device is annular and serves a helical return spring 49 as a seat between the head 26 of the flap valve 25 and the Guide core 19 of the connection 17 is arranged.

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The baffle 48 is simply under the head 26 of the flap valve 25 held by the return spring 49. The baffle 48 allows a squeezing of the turns of the spring 49 under the To avoid the effect of a considerable amount of liquid being pumped.

The spring 49 tends to move the flap valve 25 into the open position with the head 26 separated from the conical seat 18. The force of the return spring 49 is relatively weak chosen, and in practice only slightly larger than that which is necessary to accommodate the mass of the movable devices to compensate, i.e. that of the flap valve 25 and, in addition, the friction and hydraulic resistance forces taking into account the fact that the flap valve is blocked in the open position during operation.

With a view to putting the pressure vessel into operation, the valve 13 is used in the gas region 15 determined by the bladder 14 '' pressurized gas stored. The said bubble increases in volume and lies on the entire inner wall part of the Envelope 10 and closes the flap valve 25.

Then connection 17 is connected to a hydraulic system, where liquid with a higher pressure than the gas pre-pressure in the bladder 14 is introduced into the connection 17, and the flap valve 25 by penetrating into the liquid part 16 and compressing the bladder 14.

The pressure vessel is in operating condition.

In the present example, the hydraulic system is designed so that its demand for hydraulic fluid is a constant predetermined Volume corresponds to that is less than that of the liquid part 16 when the bladder 15 is in its maximum compression state is. In this way, when liquid is withdrawn from this liquid part 16, it is put into the Hydraulic system, never a deformation of the bladder 14, which increases in volume, instead of

that they would reach the flap valve 25.

In particular, the device is designed so that the liquid keitsdruck in the liquid part 16 is higher than 130% of the pre-pressure of the bladder 14 when the liquid part is at its maximum volume has reached.

If during normal operation there is a liquid with a large delivery rate is removed from the part 16 in order to be returned to the hydraulic system, the flap valve 25 tends towards being suddenly closed by the suction effect of the rapid drainage of the liquid. Thanks to the invention, the The only limitation of the liquid delivery rate is that which results from the cross section of the passages 21. Medium funding limits on the order of one hundred liters per second can be achieved with a flap valve, the passages 21 of which have a have a relatively large diameter.

When the flapper valve 25 has such a tendency to close, its stem 27 penetrates into the guide 19 and reduces this Volume of the chamber 33. Liquid is accordingly transferred from this chamber 33 into the channels 36 and 37 and into the hollow pin 39 pressed and lifts the ball 42, despite the passage through the game 47, the cross-section of which is too small to make it a to allow a considerable amount of liquid to escape via this path, on the seat 44 comes to rest. The chamber . 33 is therefore prevented from decreasing in volume, and an almost immediate hydraulic blockage of the Flap valve 25, i.e. much earlier than the head 26 can is to lean on the seat 18 (Fig. 3). So the closing of the flap valve 25 is automatically in case of a snow len liquid return avoided during operation.

The reaction time of the ball 42 as it moves between the non-tight seat 41 and the tight seat 44 can be determined by a Corresponding number of the height of the pin 40, which determines the distance between the ball 42 and the tight seat 44, can be adjusted. This adjustment can also be done by choosing doc diameter «; the

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Ball 42 with respect to the diameter of the cylindrical portion 4 3 can be determined, in which the ball 42 lies, which determines a cross-section of the passage game 47 that is far or less large. For clarification it should also be mentioned that the difference in diameter the ball 42 and the cylindrical portion 43 on the order of four and five tenths of a millimeter can lie.

Due to the maintenance requirements of the pressure vessel, there may be reasons to recycle the vessel slowly to completely empty the liquid, for example if the system is at a standstill or if a Inspection. In this case, when the flap valve 25 approaches the seat 18 and thereby reduces the volume of the chamber 33, such a process is slow. The guided from the chamber 33 into the channels 36 and 37 and into the hollow pin 39 and then into the cylindrical portion 43 incoming liquid has the opportunity to overcome overall the game 47 that around the ball 42 is provided around without lifting this ball 42 from its non-tight seat 41. The said liquid can so flow freely in the channel 45 and then be derived through the opening 35 to sen out. This is how the flap valve closes 25 under the direct thrust of the bladder, 14, which in This case is strived for, nothing to prevent it. It will be noted that the bladder 14 has very little thrust on the Flap valve 25 has to exercise to close it and therefore does not run the risk of being damaged in any way.

It becomes the most simple and convenient construction of the invention Device as well as its precise and automatic functioning can be noticed.

Furthermore, it will be noted that the invention is particularly interesting when the volume of the liquid from the pressure vessel, that can be absorbed by the hydraulic system is less than the maximum liquid volume of the liquid part 16 of the pressure vessel.

In a variant (FIG. 4), the arrangement is analogous to that described above with reference to FIGS. 1 to 3, but the The height of the non-tight seat 41 is provided in a controllable manner in the form of a disk stack 50 with a more or less large number of washers / which are arranged below the split pin 39, which allows the stroke of the ball 42 between their Seats 41 and 44 and thus adjust the response time for the hydraulic blocking in the case of rapid liquid return.

In a further variant (FIG. 5) the split pin 3S is replaced by a hollow pin 51, the upper end of which is grooved at 52 in order to form the non-tight seat 41. The height of the
Non-tight seat 41 is provided here by screwing the pin 51 into a threaded hole 53 of the guide 19 to a greater or lesser extent.

Another variant (Fig. 6) is the arrangement analogous to that
with reference to Fig. 5 described above, but the opening 35 for the passage 34 is arranged in the interior of the annular baffle 48 in such a way that this is subjected to an even further reduced pressure.

In this case, the baffle 48 allows not only to avoid that the turns of the return spring 49 under the action of a
considerable amount of liquid are squeezed, but also an even greater reduction in pressure
at the opening 35 of the passage 34. Accordingly, the
Pressure difference between the mountain and "valley sides of the ball 42
reduced, which facilitates the displacement of the ball 42 between its non-tight seat 41 and its tight seat 44. The response time for hydraulic blocking is accordingly reduced even further.

In a further variant (FIG. 7) the arrangement is always
still analogous to those described above, but the sealing element is formed here by a plunger 42 ′ which is movably mounted in the cylindrical section 43.

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The means for slow passage here consist of one or more channels arranged in the plunger 42 '.

The rest support 41 for the sealing member 42 'consists of one Seat 55, which may be tight in itself, but which is connected to a drainage channel through a bore 56 in the hollow pin 51 is formed. The way it works is analogous to that described above.

In a further variant (FIG. 8), the arrangement is analogous to that described with reference to FIG. 7, but the Means for the slow passage of liquid here consist of one or more channels, such as grooves 54 'formed on the Outer wall of the plunger 42 'were created.

In another variant (FIG. 9), the arrangement is analogous to that described with reference to FIG. 8, but the rest support 41 for the sealing element 42 ', which is formed by the seat 55, which is sealed per se, is connected to a directly in the shaft 27 of the Flap valve 25 provided discharge channel 56 ". In addition, the grooves 54 'of FIG. 8 are here by grooves 54". which are formed in the inner wall of the cylindrical portion 43.

In a further variant (Fig. 10) the sealing member, which consists of a ball, for example the ball 42, is suitable to lie on a flat bottom 57 of section 43, while a channel 56 ″ analogous to the channel 56 * is provided between the chamber 33 and the section 4 3.

In the above, the movable separator consists of a deformable bladder 14, but it could also be replaced by a Pistons are formed. Furthermore, the pressure vessel was described in the form of a hydropneumatic pressure accumulator, he however, could also be formed by any other suitable type of pressure vessel.

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Claims (21)

- OS- - 21,370 / ki PATENT CLAIMS ί 1)! Flap valve for pressure vessels, the said pressure vessel has a dimensionally stable envelope 10 which has a gas opening 11 and an opposing fluid port 12, a movable one located inside the envelope 10 between the aforesaid two openings 11, 12 and these in a gas part 15 and a Liquid part 16 having variable volumes separating divider 14, said flap valve 25 having a movable, Shank 27 mounted in a guide 19 and a head 26 suitable for closing the liquid opening 12 has, said shaft 27 forming a fluid chamber 33 of variable volume with said guide 19, said chamber 33 then being reduced in volume as shaft 27 penetrates and said chamber 33 through passage means 34 with an opening 35 in connection, which is in the vicinity of the head 26 of the flap valve 25 is, characterized in that said passage means 34 on the one hand interruption means 42,42 'for the drainage of the liquid from the named th chamber 33, when said chamber 33 decreases in volume, and on the other hand means for slow passage 47 between said chamber 33 and an active part of said interrupting means 42, 42 'for the drainage of the liquid exhibit. 2) flap valve according to claim 1, characterized in that the said passage means 34 a cylindrical portion 43, which at its opening 35 of said through step means 34 at the nearest end a tight fit 44 has, while said interrupter means have a sealing member 42,42 'which is movably mounted in said section 43 and is suitable to be pushed by the liquid in order to close due to a. Reduction of the volume of said chamber 33 to support the th seat 44 , said means for slow passage 47 constantly the two parts 43A, 43B of section 43, which are on both sides of the sealing member 42 ,, 42 ' are arranged to keep in touch. 3) flap valve according to claim 2, characterized in that the cylindrical portion 43 of the liquid passage 44 at its end opposite to the tight seat 4 4 and closest to the chamber of variable volume 33 a support 41 to support the sealing member 42,42 'thereon , to which the latter tends to be brought back by a weak spring 46, said support being suitable, to pass the drain between said chamber 33 and said section 43. 4) flap valve according to claim 3, characterized in that said support 41 through one end of a hollow pin 39 is formed, which is split at 40 (Fig. 2 or Fig. 4) 5) flap valve according to claim 3, characterized in that said seat 41 by a grooved end 52 of a hollow pin 51 is formed (Fig. 5 or Fig. 6). 6) flap valve according to claim 3, characterized in that said seat 41 through one end of a hollow pin 51 formed and with a diversion channel 56, 56 '(Figures 7 to 9) is connected. 7) flap valve according to claim 3, characterized in that said seat is formed by a bottom 57 of said cylindrical Section 4 3 is formed and is connected to a discharge channel 54 ″ (FIG. 10). 8) Flap valve according to Claims 3 to 7, characterized in that control devices for adjusting the height of the seat 41 are provided. 9) flap valve according to claim 8, characterized in that said Regoleinrichtung a stack of discs 50 in larger or a smaller number (Fig. 4 or Fig. 7). - -T7 - -3- 10) flap valve according to claim 8, characterized in that the control devices have a screw connection 53 (Fig. 5 or Fig. 6). 11) flap valve according to claims 2 to 10, characterized in that that the closure member consists of a ball 42 (Figures 1-6). 12) flap valve according to claims 2 to 10, characterized in that that the closure member consists of a plunger 42 ' (Figures 7 to 9) consists. 13) flap valve according to claims 2 to 12, characterized in that that the means for slow passage from a slight diametrical play 47 between the closure member 42 and the cylindrical portion of the passage 43 (Figs. 2 and 10) exist. 14) flap valve according to claims 2 to 12, characterized in that that the means for slow passage consist of at least one narrow channel 54,54 'formed in the closure member 42 * is provided (Figures 7 and 8). 15) flap valve according to claims 2 to 12, characterized in that that the means for slow passage from at least one in the stem 27 of the flap valve 25 is created narrow channel 54 "exist (Figure 9). 16) flap valve according to claims 1 to 15, characterized in that that the opening 35 of the passage 34 is arranged directly below the head 26 of the flap valve 25. 17) flap valve according to claims 1 to 16, characterized in that that an annular baffle 48 is arranged below the head 26 of the flap valve 25. - 4-8- - -S. 18) flap valve according to claim 17, characterized in that the opening 35 of the passage 34 inside said annular baffle 48 is arranged (Fig. 6). 19) flap valve according to claim 17 or 18, wherein the flap valve 25 is retained by a spring 4 9 in the open position of the liquid opening 12, characterized in that that said annular guide plate 48 for said return spring 49 forms a seat. 20) flap valve according to claims 1 to 19, in which the flap valve 25 is retained by a spring 49 in the open position of the liquid opening 12, characterized in that that the force of this return spring 49 is weak .and only slightly larger than that which is necessary is the mass of the flap valve. 25 plus the frictional forces and to compensate for the hydraulic resistance. 21) Flap valve for pressure vessels, said pressure vessel has a dimensionally stable envelope 10 which has a gas opening 11 and an opposing liquid port 12, a movable, inside the shell 10 between the two openings 11, 12 mentioned and these in a gas part 15 and a liquid part 16 with variable volumes separating divider 14, said flap valve 25 being a movable, mounted in a guide 19 shaft 27 and a for closing the liquid opening 12 has a suitable head 26, said shaft 27 with said Guide 19 forms a fluid chamber 33 of variable volume, one created in the flap 25 and between the named chamber 33 and an opening 35 located under the head 26 of the flap valve 25, characterized in that said passage 34 has a cylindrical portion 43 which on the one hand at its end located closest to the opening 35 of said passage 34 with a seal Seat 4 4 and, on the other hand, at its end closest to said chamber 33 with a non-tight seat 41 is provided, while a ball 4 2 is movable in this section 43 is mounted and retained by a spring 46 on the non-tight seat 41 and is suitable from the Liquid to be pushed in order to finally sit down on the tight seat 44 when a volume reduction said chamber 33 enters through a slow passage means of reduced cross-section which passes through a slight diametrical play is formed between the ball 42 and the section 43 and an annular guide plate under the head 26 of the flap valve 25 to form a seat for a weak return spring 49 of the flap valve 25 in the open position.